The present invention relates in general to brain lesioning methods and apparata. More particularly, the present invention relates to a combination system for brain lesioning which initially uses a separate visualization system for site localization. The data from the visualization system is digitized and translated by computer into linear and rotary positioning means for positioning the ultrasound transducer which is used to create volume lesions. The separate visualization system may be a CT or MRI scan or may be ultrasonic imaging. The required output in the depicted configuration is a transparency of the imaged tumor or other volume to be lesioned which can then be translated into a computer by use of a digitizing tablet.
Traditionally, the selected method for treatment of brain tumors and related disorders was to first take and process an X-ray film of the brain and from that film roughly determine the size, shape and location of the tumor. The next step was to surgically remove as much of the tumor as possible. As technology has advanced, X-ray usage has yielded to other visualization methods, such as ultrasound, CT scan techniques and MRI utilization. The surgical procedures have expanded to cryoknives and gamma knives. Radon seeds have been implanted and ionizing radiation used. Each of these approaches has met with some success but not without their share of adverse side effects, including incomplete treatment.
Any cutting procedure is risky, especially in the area of the brain, in that the procedure may result in the incomplete removal of the tumor tissue, the excess removal of healthy tissue, or both. Ionizing radiation creates a cumulative effect of the dosage to the other, surrounding brain tissue. These concerns and their attendant problems are addressed and solved by the use of ultrasound to produce volume lesions in the brain. As is well known, the noninvasive nature of ultrasound provides a safe and convenient means of treatment by selection of a suitable dosage to produce volume lesions.
The success of any ultrasound approach depends on a number of factors. Not only must the dosage (intensity and time) be controlled, but the alignment of the beam, spot size and completeness of the treatment over the full volume of the tumor or other selected tissues are critical. An added concern with the treatment of brain tumors with ultrasound is the risk of "skimming" of the ultrasound beam by the edge of the bony opening in the skull. Finally, since ultrasound is not a "sighted" treatment technique, the physician needs to have some means of determining the exact location of the tumor, its size and its shape.
The number of engineering and anatomical concerns over the use of ultrasound for treatment of brain tumors has meant that over the years there has been very little interest in producing volume lesions in the brain for the elimination of tumors. The inability to deal with these engineering and anatomical concerns has meant that a valuable treatment option has not been adequately utilized. There is no doubt that noninvasive ultrasound is preferred over the surgeon's scalpel. What has been missing and what is provided by the present invention is a means to translate the tumor location and shape determination data from a reliable imaging technique such as ultrasound, CT scan or MRI into computer-controlled linear and rotary drive means for the ultrasound transducer. By digitizing the ultrasound, CT scan or MRI data, alignment of the focused ultrasound beam can be precise and the dosage determined so as to be able to use ultrasound to produce volume lesions in the brain for the treatment of tumors. The present invention provides a number of unique and valuable structures which cooperate to provide an apparatus which is both extremely accurate and precise, and which avoids the prior art problems.